184. 部门工资最高的员工
题目
Employee 表包含所有员工信息,每个员工有其对应的Id, salary 和 department Id。
Id | Name | Salary | DepartmentId |
---|---|---|---|
1 | Joe | 70000 | 1 |
2 | Jim | 90000 | 1 |
3 | Henry | 80000 | 2 |
4 | Sam | 60000 | 2 |
5 | Max | 90000 | 1 |
Department表包含公司所有部门的信息。
Id | Name |
---|---|
1 | IT |
2 | Sales |
编写一个 SQL 查询,找出每个部门工资最高的员工。对于上述表,您的 SQL 查询应返回以下行(行的顺序无关紧要)。
Department | Employee | Salary |
---|---|---|
IT | Max | 90000 |
IT | Jim | 90000 |
Sales | Henry | 80000 |
解释:
Max 和 Jim 在 IT 部门的工资都是最高的,Henry 在销售部的工资最高。
题解
SELECT `Department`.`Name` AS `Department`, `Employee`.`Name` AS `Employee`, `Employee`.`Salary` AS `Salary`
FROM `Employee`
INNER JOIN (
SELECT MAX(`Salary`) AS `Salary`, `DepartmentId` FROM `Employee` GROUP BY `DepartmentId`
) `t` ON `t`.`DepartmentId` = `Employee`.`DepartmentId` AND `Employee`.`Salary` = `t`.`Salary`
INNER JOIN `Department` ON `t`.`DepartmentId` = `Department`.`Id`